Fast food restaurants have commonly prepackaged the individual components of a hot meal and placed it on a warming tray or under infrared lamp to keep the food warm until sale and consumption. With the standard sandwich menu of many fast food and carry-out restaurants, these individual packages proved adequate; however, for certain items of the menu, the individual packages proved unsatisfactory, and therfore difficulties were experienced in preparing and packaging these foods ahead of time.
It is desirable that certain items in fast food or drive-in restaurants be capable of being prepared prior to the actual sale and stored for a short period of time in a hot and appetizing condition until sale to a patron. Storage in fast food restaurants generally presents the problem of the efficient use of space. If the prepared food requires a large amount of space by reason of its numbers or size, restaurant operators will stack the individual food items vertically to conserve in space and also to more efficiently dispense the food items.
With individual items, the use of a container roughly the size of the sandwich, having a hinged top for easy access to the food item and composed of a polystyrene material, has proven itself very desirable, for a number of reasons, in keeping the food hot and fresh during the temporary storage period prior to consumption. Due to its relatively small size, there is sufficient structural strength provided by the corners of such a container so that it may be efficiently stacked and stored in large quantities yet only a small amount of counter space is utilized.
However, when such a container is made larger for use with standard meals, such as scrambled eggs and sausage, or perhaps a chicken dinner, it has been found that the hot temperatures at which it is necessary to keep the food can destroy the structural integrity of the polystyrene material and render the packages incapable of being stacked for efficient storage. If a conventional disposable plate and lid or cover were used, those high temperatures necessary for, say, some breakfast items, would cause the plastic material of which it is formed to lose its structure and sag. In so doing, a stack of these conventional plates and lids, when filled with hot food items, would sag, thereby collapsing the plates and lids and crushing the food or unbalancing the stack and causing the stack to topple. Further, even though the temperatures may not be high enough to cause sagging and the subsequent toppling of the packages, the temperature of the stacked packages may be sufficiently high to cause the polystyrene material packages to stick to one another in an undesirable manner.